Table 2.
Ampicillin PDAE Among Very Low Birth Weight Infants by Susceptibility Breakpoints of Common Bacterial Pathogensa,b
| 2 Dosesc | 4 Dosesc | 6 Doses | ||||
|---|---|---|---|---|---|---|
| Organism | Susceptible MIC (mcg/mL) | 50 mg/kg Q12 h | 100 mg/kg Q12 h | 50 mg/kg Q12 h | 100 mg/kg Q12 h | 100 mg/kg Q8 h |
| Escherichia coli d | 8 | 34 ± 9.4 (17, 54) | 42 ± 11 (22, 66) | 36 ± 11 (18, 60) | 46 ± 13 (22, 72) | 50 ± 14 (24, 79) |
| 4 | 42 ± 11 (22, 66) | 51 ± 13 (26, 78) | 46 ± 12 (23, 72) | 55 ± 15 (26, 84) | 60 ± 16 (27, 91) | |
| Listeria monocytogenes | 1 | 60 ± 15 (30, 90) | 72 ± 18 (34, 103) | 64 ± 17 (30, 97) | 74 ± 19 (35, 109) | 80 ± 20 (36, 116) |
| Group B Streptococcuse | 0.25 | 82 ± 19 (39, 114) | 96 ± 21 (42, 126) | 84 ± 21 (39, 120) | 94 ± 21 (43, 126) | 104 ± 20 (44, 122) |
Abbreviations: MIC, minimum inhibitory concentration in mcg/mL; PDAE, post-discontinuation empiric antibiotic exposure; Q8, every 8 h; Q12, every 12 h.
aNumbers represent mean ± standard deviation (95% confidence interval) for the duration of therapeutic exposure (hours) from the last dose of ampicillin up to the MIC of bacterial pathogens commonly isolated in early-onset sepsis.
bInfusion time for ampicillin was 15−30 min.
cLast dose was 12 h for 2 doses, 36 h for 4 doses, and 40 h for 6 doses.
dMIC of 8 mcg/mL is also the breakpoint for Enterococcus spp.
eMIC of 0.25 mcg/mL is also the breakpoint for Streptococci groups A, B, C, and G; Viridans streptococci have MIC breakpoint of 0.5 mcg/mL.